Friction in lubricated engine bearings, such as camshaft bearings, contributes to a vehicle's fuel economy. The friction depends, at least in part, on engine oil viscosity, which is a function of engine oil temperature. Thus, the temperature of the engine oil contributes to the fuel consumption and emissions of the internal combustion engine.
Oil systems may be provided where oil is drawn from a sump and provided to various engine components before being returned to the sump. While various approaches, such as electric heaters and other waste heat recovery mechanisms may be used to provide increased heat to the oil, the inventors herein have recognized that there is still a delay in heating up all of the oil in the system so that sufficiently heated oil is drawn from the sump and delivered to the engine components for lubrication.
As described herein, one approach to address the above issues includes supplying engine oil from a higher pressure oil pump side to reciprocating engine components, where at a first condition, at least some engine oil downstream of the reciprocating engine components is diverted around an oil sump to a lower pressure oil pump side via a bypass line. Further, at a second condition, engine oil downstream of the reciprocating engine components may be routed to the oil sump, for example in a path separate from the bypass line.
In this way, it is possible to provide the available engine heat and friction heat from the engine components to a smaller volume of oil, where that smaller volume of oil is preferentially used as compared to colder oil in the sump. As such, the oil actually provided to the engine components heats up more rapidly for a given amount of heat input, whether from friction, waste heat recovery, electric heater, and the like, which may be used, if desired. Then, once sufficient warm-up has occurred where substantially all of the engine oil, including oil in the sump, has reached a desired operating temperature, the bypass oil line may be disabled. As such, during over-temperature conditions, the full oil supply is available to reduce oil over-heating.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.